Floorboards with decorative grooves

ABSTRACT

Floorboards which have a core and a surface layer and are provided with decorative joint edges which are formed by removing the surface layer. A method for making a floorboard, or a floor element that is to be divided into at least two floorboards, the method including making a core from a sheet shaped material, from which a part of a locking system for vertical locking of the floorboards is to be formed, impregnating and/or staining the core surface with a substance at least in portions which in the completed floorboard will constitute a joint edge of the completed floorboard, and arranging an surface layer on the core surface.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.14/184,382, filed on Feb. 19, 2014, which is a continuation of U.S.application Ser. No. 13/045,631, filed on Mar. 11, 2011, now U.S. Pat.No. 8,683,698, which is a continuation of U.S. application Ser. No.10/508,198, filed on Jun. 29, 2005, now U.S. Pat. No. 7,926,234, whichis a National Stage Application of PCT Application No. PCT/SE03/00471,filed on Mar. 20, 2003, which claims the benefit of PCT Application No.PCT/SE02/01731, filed on Sep. 20, 2002, and the benefit of SwedishApplication No. 0200848, filed on Mar. 20, 2002. The entire contents ofeach of U.S. application Ser. No. 14/184,382, U.S. application Ser. No.13/045,631, U.S. application Ser. No. 10/508,198, PCT Application No.PCT/SE03/00471, PCT Application No. PCT/SE02/01731 and SwedishApplication No. 0200848 are hereby incorporated herein by reference.

TECHNICAL FIELD

The invention generally relates to the field of decorative grooves forfloorboards. The invention relates to floorboards provided with suchdecorative grooves and methods for making such floorboards. Theinvention is particularly suited for use in mechanical locking systemsintegrated with the floorboard of the type described and shown, forexample, in WO9426999, WO9966151, WO9966152, SE 0100100-7 andSE0100101-5 (owned by Välinge Aluminium AB) but is also usable inoptional joint systems which can be used to join floors.

More specifically, the invention relates above all to floors of the typehaving a core and a decorative surface layer on the upper side of thecore.

FIELD OF APPLICATION OF THE INVENTION

The present invention is particularly suitable for use in floatingfloors, which are formed of floorboards which are joined mechanicallywith a joint system integrated with the floorboard, i.e. mounted at thefactory, and are made up of one or more preferably moisture-proof upperlayers of decorative laminate or decorative plastic material, anintermediate core of wood-fibre-based material or plastic material andpreferably a lower balancing layer on the rear side of the core. Thefollowing description of prior-art technique, problems of known systemsand objects and features of the invention will therefore, as anon-restrictive example, be aimed above all at this field of applicationand in particular laminate flooring formed as rectangular floorboardsintended to be mechanically joined on both long sides and short sides.However, it should be emphasized that the invention can be used inoptional floorboards with optional joint systems, where the floorboardspreferably have a core and at least one surface layer and where thesetwo parts have, or in connection with manufacture can obtain, differentdecorative properties in the form of colour, pattern, structure or thelike. The invention can thus also be applicable to, for instance, floorswith one or more surface layers of wood, plastic material, flexiblefibres such as needle felt or combinations of different materials, forinstance wood, plastic, cork, rubber or other materials that are used assurface layers in floors. The invention can also be used to formdecorative joint portions in homogeneous materials such as homogeneouswooden floors.

BACKGROUND OF THE INVENTION

Laminate flooring usually consists of a core of a 6-9 mm fibreboard, a0.2-0.8 mm thick upper decorative surface layer of laminate and a0.1-0.6 mm thick lower balancing layer of laminate, plastic, paper orlike material. The surface layer provides appearance and durability tothe floorboards. The core provides stability, and the balancing layerkeeps the board plane when the relative humidity (RH) varies during theyear. Laminate flooring can also be made of compact laminate. Surfacelayer and balancing layer are then applied to a core ofphenol-impregnated kraft paper or phenol-impregnated wood fibres.Manufacture of surface layer, core and balancing layer takes place whilepressure and heat are being supplied. The floorboards are usually laidfloating, i.e. without gluing, on an existing subfloor which does nothave to be completely smooth or plane. Any irregularities are eliminatedwholly or partly by means of base material in the form of e.g. board orfoam which is placed between the floorboards and the subfloor.Traditional hard floorboards in floating flooring of this type areusually joined by means of glued tongue-and-groove joints (i.e. jointsinvolving a tongue on one floorboard and a tongue groove on an adjoiningfloorboard) on long side and short side. When laying the floor, theboards are brought together horizontally, whereby a projecting tonguealong the joint edge of one board is introduced into a tongue groovealong the joint edge of an adjoining board. The same method is used onthe long side as well as on the short side.

In addition to such traditional floors, which are joined by means ofglued tongue-and-groove joints, floorboards have recently been developedwhich do not require the use of glue and instead are joined mechanicallyby means of so-called mechanical joint systems. These systems compriselocking means which lock the boards horizontally and/or vertically. Themechanical joint systems can be formed by machining of the core of theboard. Alternatively, parts of the locking system can be formed of aseparate material, which is integrated with the floorboard, i.e. joinedwith the floorboard even in connection with the manufacture thereof.Separate materials can either be fixedly secured to the floorboardmechanically, by means of glue and the like. They can also bemechanically secured in such a manner that they can, for instance, bedisplaced along the joint edge or be detached by an angular motion.

The main advantages of floating floors with mechanical joint systems arethat they can easily and quickly by laid by various combinations ofinward angling, snapping-in and displacement along the joint edge.Snapping-in can take place by displacement of the joint edgeshorizontally, vertically or at different angles. The floorboards canalso easily be taken up again and used once more at a differentlocation. A further advantage of the mechanical joint systems is thatthe edge portions of the floorboards can be made of materials which neednot have good gluing properties.

The most common core material is a fibreboard with high density and goodstability usually called HDF—High Density Fibreboard. Sometimes alsoMDF—Medium Density Fibreboard—is used as core. As a rule, these corematerials are of high quality and often have an attractive surface whichcan resist penetration of moisture.

Thick surface layers of wood, for instance 1-4 mm, are usually appliedto a core consisting of wood blocks whose fibre direction isperpendicular to the fibre direction of the surface layer. Particleboard, fibreboard or plywood are also used both when the surface layeris thick and also when the surface layers are thin veneer with athickness of e.g. 0.2-1.0 mm.

Laminate flooring and also many other floorings with a surface layer ofplastic, wood, veneer, cork and the like are made by the surface layerand the balancing layer being applied to a core material. Thisapplication may take place by gluing a previously manufactureddecorative layer, for instance when the fibreboard is provided with adecorative high pressure laminate which is made in a separate operationwhere a plurality of impregnated sheets of paper are compressed underhigh pressure and at a high temperature. The currently most commonmethod when making laminate flooring, however, is direct laminatingwhich is based on a more modern principle where both manufacture of thedecorative laminate layer and the fastening to the fibreboard take placein one and the same manufacturing step. Impregnated sheets of paper areapplied directly to the board and pressed together under pressure andheat without any gluing.

In addition to these two methods, a number of other methods are used toprovide the core with a surface layer. A decorative pattern can beprinted on the surface of the core, which is then, for example, coatedwith a wear layer. The core can also be provided with a surface layer ofwood, veneer, decorative paper or plastic sheeting, and these materialscan then be coated with a wear layer.

As a rule, the above methods result in a floor element in the form of alarge board which is then sawn into, for instance, some ten floorpanels, which are then machined to floorboards. The above methods can insome cases result in completed floor panels and sawing is then notnecessary before the machining to completed floorboards is carried out.Manufacture of individual floor panels usually takes place when thepanels have a surface layer of wood or veneer.

In all cases, the above floor panels are individually machined alongtheir edges to floorboards. The machining of the edges is carried out inadvanced milling machines where the floor panel is exactly positionedbetween one or more chains and bands mounted, so that the floor panelcan be moved at high speed and with great accuracy past a number ofmilling motors, which are provided with diamond cutting tools or metalcutting tools, which machine the edge of the floor panel. By usingseveral milling motors operating at different angles, advanced jointgeometries can be formed at speeds exceeding 100 m/min and with anaccuracy of ±0.02 mm.

Definition of Some Terms

In the following text, the visible surface of the installed floorboardis called “front side”, while the opposite side of the floorboard,facing the subfloor, is called “rear side”. The sheet-shaped startingmaterial that is used is called “core”. When the core is coated with asurface layer closest to the front side and preferably also a balancinglayer closest to the rear side, it forms a semi-manufacture which iscalled “floor panel” or “floor element” in the case where thesemi-manufacture, in a subsequent operation, is divided into a pluralityof floor panels mentioned above. When the floor panels are machinedalong their edges so as to obtain their final shape with the jointsystem, they are called “floorboards”. By “surface layer” are meant alllayers applied to the core closest to the front side and coveringpreferably the entire front side of the floorboard. By “decorativesurface layer” is meant a layer which is mainly intended to give thefloor its decorative appearance. “Wear layer” relates to a layer whichis mainly adapted to improve the durability of the front side. In alaminate floor, this wear layer often consists of a transparent papercontaining melamine and aluminum oxide. By “reinforcing layer” is meanta layer which is mainly intended to improve the capability of thesurface layer of resisting impact and pressure and, in some cases,compensating for the irregularities of the core so that these will notbe visible at the surface. In high pressure laminates, this reinforcinglayer usually consists of brown kraft paper which is impregnated withphenol resin. By “decorative layer” is meant a layer which is applied tothe reinforcing layer in an analog manner, i.e. under the decorativesurface layer, but with a view to achieving a predetermined appearance,rather than a reinforcing effect. The decorative layer can be identicalwith the reinforcing layer by this being stained or modified in someother manner to obtain a desired appearance.

By “the part of the core which is closest to the surface layer” isgenerally meant the part of the core which is positioned above thevertical locking means, and preferably at a shorter distance from thesurface layer of the core than from the vertical locking means.

Regarding “plywood”, which consists of several layers of crosswisejoined layers of wood, the inner layers of the plywood are to beconsidered to constitute a core, the outer layers being considered toconstitute surface layer, reinforcing layer and/or decorative layer,according to the definitions above.

By “horizontal plane” is meant a plane which is parallel to the outerpart of the surface layer. In the joined position, the two juxtaposedupper joint edges define a “vertical joint plane”.

The outer parts of the floorboard at the edge of the floorboard betweenthe front side and the rear side are called “joint edge”. As a rule, thejoint edge has several “joint surfaces” which can be vertical,horizontal, angled, rounded, beveled etc. These joint surfaces can bemade of different materials, for instance laminate, fibreboard, wood,plastic, metal (e.g. aluminum) or sealing material. By “joint edgeportion” are meant the joint edge of the floorboard and part of thefloorboard portions closest to the joint edge. By “decorative jointportion” is generally meant part of the surface of the floorboard whichis intended to resemble a visible joint between, for instance, stone orwood material.

By “joint” or “joint system” are meant coacting connecting means whichconnect the floorboards vertically and/or horizontally. In connectionwith joining of the floorboards, “vertical” means a direction which isperpendicular to the horizontal plane. “Horizontal” means a directionwhich is perpendicular to the vertical joint plane of the respectivejoints.

The above techniques can be used to manufacture laminate floorings whichare highly natural copies of wooden flooring. In recent years,imitations of stones, tiles and the like have become more and morecommon. In this context, it is tried to manufacture decorative jointportions between stones and tiles which should be as natural aspossible. They should have decoration and structure other than those ofthe stone material and should also be somewhat lowered under thehorizontal plane to resemble an embedded joint between two stones ortiles. The techniques used to manufacture these decorative jointportions are expensive and do not provide a natural appearance. Itshould be possible to increase the market for these types of flooringsignificantly if decorative joint edge portions could be made in asimpler and less expensive manner and with a more natural appearance.

PRIOR-ART TECHNIQUE AND PROBLEMS THEREOF

When making laminate flooring with decorative and embedded jointportions, the starting material is a decorative paper with printed jointedge portions. This paper is usually impregnated with melamine resin.Uncontrolled swelling takes place in this operation. In the subsequentlamination, the decorative impregnated paper is placed on a core. Atransparent wear layer is preferably placed over this decorative paperand then lamination takes place against an embossed metal sheet, inwhich joint portions are formed which usually have a structure differentfrom that of the remaining part of the metal sheet and where jointportions are designed so that a depression of 0.2 mm can be provided inconnection with laminating. The result is a floor element whose frontside has an embedded joint pattern corresponding to the intended jointportions between, for instance, tiles or stones.

This manufacturing method suffers from a number of problems which areabove all related to difficulties in positioning the decorative paperand metal sheets in connection with laminating and the difficulty inpositioning floor element and floor panels in the subsequent sawing andmachining of the joint edges.

The metal sheet must be positioned with great accuracy relative to thedecorative paper. Even if this is carried out with extremely greataccuracy, it is not possible to eliminate the uncontrolled swelling inconnection with impregnating. This swelling also causes problems in thesawing operation and machining of joint edges. The result of theseswelling and positioning problems is that decoration and embossing donot agree with each other and that the decorative embedded jointportions vary between different floorboards, which results in anunnatural appearance.

To counteract these problems, different methods have been used. Onemethod is to limit the format of the floor element so as to thus reducethe maximum deviation in connection with swelling. Special marks aremade on the decorative paper which can then be read optically inconnection with pressing and sawing. Then the boards are aligned asaccurately as possible and individual adjustment of the saw blades canbe made for each floor element.

The main disadvantage of this method is high cost, low capacity andextremely great remaining deviation between decoration, embossing andjoint edge in the completed floorboard.

It is also difficult to provide a deep depression in high pressurelaminate without damaging the decorative paper. Depressing of jointportions in connection with direct lamination results in fibres of thecore being compressed. The compressed fibres can later, if moisturepenetrates, swell more than normal and cause damage to the joint edge.

It is known that laminate floor or wooden floor can have an upper jointedge which is rounded or beveled at an angle of 35-45 degrees. This typeof edge machining which is mainly intended to reduce the problems withdifferent vertical positions between two joint edges is not suitable toprovide the design of the edge which the present invention can provide.

BRIEF DESCRIPTION OF THE INVENTION AND OBJECTS THEREOF

An object of the present invention is to eliminate or reduce one or moreof the problems occurring in connection with manufacture and use offloorboards with decorative embedded joint portions. A further object ofthe invention is to provide a rational and cost-efficient manufacturingmethod for manufacturing floor elements, floor panels and floorboards.

The above objects are wholly or partly achieved by systems, floorboardsand methods according to the independent claims. Embodiments of theinvention are evident from the dependent claims as well as from thedescription and drawings.

The invention is based on the knowledge that the decorative jointportions should be made in connection with the machining of the jointedges of the floor panel. Laminating and sawing can then take placewithout any specific requirements as to alignment, and swelling problemsdo not occur.

The decorative and embedded joint portion can be provided by part of thesurface layer, preferably the decorative surface layer, being removed tosuch an extent that an underlying layer is uncovered, which layer has adesired decorative effect. This underlying layer can be, for instance, asurface layer which is a reinforcing layer, a decorative layer or anuncovered part of the core of the floorboard. According to anembodiment, machining takes place to such a depth that the decorativesurface layer is removed and it is ensured that the underlying layer isuncovered. According to an embodiment, the machining of the underlyinglayer can be limited to what is necessary to achieve the desired effect.Thus, machining can be carried out to such a depth that the surfacelayer, at the joint edge, is completely removed, but without completelyremoving the underlying layer. This may in some cases result in theremoving of material, for the purpose of completely removing the surfacelayer, being allowed to extend slightly into the underlying layer.

The decorative joint portion can also be provided by machining whichremoves all surface layers so that the core becomes visible. Also inthis case, the depth of machining can be limited to the parts of thecore which are closest to the surface layer.

According to an embodiment, the depth of machining is very small inrelation to the thickness of the floorboard. Such shallow grooves give anumber of advantages, for instance that decorative grooves can beprovided which do not collect dirt and which are easy to clean. Otheradvantages imply that machining in the surface layers or in the coreparts closest to the surface layers need not cause deterioration of thefloorboard in terms of durability, impact strength or moistureresistance.

We have discovered that with suitable working machines and diamondcutting tools, it is possible to make a partial removal of the surfacelayer with an accuracy of 0.01 mm. The surface layer can thus be removedpartially and the underlying layer can be uncovered. This underlyinglayer can be given an appearance and structure that deviate from theremaining surface of the floorboard and can thus constitute an embeddeddecorative joint portion.

The invention is particularly suited for use in the joint edge portionsof the floorboards, but one or more decorative embedded groovesaccording to the invention can also be arranged at an optional locationbetween the joint edge portions of the floorboards.

Thus the floorboard can have a surface that consists of a plurality ofsurface portions with decorative embedded grooves between theseportions, thereby forming a surface pattern with a plurality of tiles orelongate blocks or the like. The decorative portion can be placedoptionally on the surface of the floorboard and it can have an optionalextent or shape. The decorative joint portion can be positioned on bothadjoining edges of two joined floorboards. The decorative joint portioncan also be positioned on one edge only. The joint portion can, but neednot, have an extent that covers the entire joint edge. The decorativejoint portion can be parallel with the joint edge, but it may also havea deviating shape, for instance wave-shaped, toothed, wedge-shaped andthe like. Such shapes can be achieved, for example, by machining usingan oscillating tool, or by machining using an angled tool with anembossed surface. Nor does the decorative joint portion need to have thesame depth from the floor surface along its entire extent or between twoadjoining joint edges.

The invention is also particularly suited for use with floorboardshaving mechanical joint systems which allow exact positioning of thefloorboards relative to each other without visible joint gaps in thedecorative joint portion. Such locking systems give the decorative jointportion a natural appearance.

According to a first aspect of the invention, a system is provided formaking a decorative joint portion between two adjoining joint edges offloorboards which have a core and a surface layer which is arranged onthe upper side of the core as well as connecting means arranged at saidadjoining joint edges for connecting the floorboards with each other inthe vertical and/or horizontal direction, the parts of the surface layerclosest to said adjoining joint edges forming a horizontal plane, andthe surface layer comprising an upper layer and an underlying layer. Thesystem is characterized in that at least one of said adjoining jointedges has a surface which consists of the underlying layer and which isessentially parallel to the horizontal plane.

According to this aspect of the invention, the decorative visiblereinforcing layer can be made in a number of different ways. The kraftpaper which constitutes the reinforcing layer can be wholly or partlystained in the parts that will later constitute the decorative jointportions. The partial staining can take place with overmeasure so as notto cause positioning problems in the rest of the production process.Phenol or melamine resin that is used in impregnation can be stained.Decorative reinforcing layers can be arranged both in manufacture offloorboards with surface layers of high pressure laminate and directlaminate. Surface layers of plastic or several layers of decorativeveneer layers can in the same way be machined for the purpose ofproviding decorative joint portions.

The machining extends preferably to a depth which is at least 0.1 timesthe thickness of the surface layer, counting from the upper side of thesurface layer, provided that this is sufficient to uncover an underlyinglayer.

The extent of the machining counting from the joint plane and inwards isselected so that a groove of a desired width is formed. When selectingthe width of the groove, it is also taken into consideration whetheronly one or both of two adjoining floorboards are to be provided withdecorative grooves, the grooves of each floorboard being given asuitable width.

For instance, the extent of the machining counting from the verticaljoint plane and inwards to the floorboard can also be at least 0.1 timesthe thickness of the floorboard. Such a decorative joint portion issuitable to resemble a joint gap between homogeneous parquet blocks orfloorboards of wood. The uncovered reinforcing layer, counting from thevertical joint plane, may also have an extent corresponding to about0.25 times the thickness of the floorboard. Such a decorative jointportion is suitable to resemble a joint between two stone slabs. Thedecorative joint portion may also have an optional horizontal extentwithin the range 0.1-1.0 times the thickness of the floorboard. Innormal laminate floors with a thickness of 6-9 mm, such decorative jointportions may suitably be formed with a horizontal extent correspondingto, for instance, 0.5-3.0 mm.

According to a second aspect of the invention, surface layers on thecore may be removed so that the core becomes visible. The core can thusbe used to create a decorative embedded joint portion, either by thecore having suitable properties, or by part of or the entire core beforelaminating, or after machining, being machined in a convenient manner soas to provide a decorative appearance or better properties in order tocounteract moisture or wear.

We have discovered that mechanical joint systems as a rule require theuse of relatively qualified core materials to provide a mechanical jointsystem with sufficient strength and a good function. Such high qualitycore materials, however, are not used for decoration purposes since theyare concealed by the surface layer.

According to the second aspect of the invention, the decorative jointportion is formed by the surface layer being removed and the core beinguncovered within areas that are to constitute the decorative jointportion.

HDF and plastic materials are particularly convenient in this context.HDF boards can, for instance, be stained using different colorants evenin manufacture, and portions of the core can be reinforced byimpregnating before or after laminating, using chemicals such asmelamine, phenol, polyurethane and the like. The uncovered core can, forinstance, be impregnated after machining. This impregnation can takeplace with great accuracy, using chemicals such as various types of oilor wax. These agents can penetrate into the core and they can be drawnin under the laminate surface. By suitable machining, the visible coresurface can be machined with very high precision. It is advantageous ifmachining occurs to a depth which is marginally greater than the surfacelayer. The advantage is that such decorative joint portions do notcollect dirt. If the surface layer is directly laminated, such machiningwill also cause the surface of the uncovered core to have goodproperties in terms of moisture and wear. We have discovered that coreparts immediately under the surface layer are impregnated with melaminein connection with the laminating process when the melamine-impregnatedpaper is pressed against the core. The melamine penetrates about 0.2-0.4mm into the core under the surface layer and bonds the wood fibres. Thedepth of penetration and the amount of melamine depend on the laminatingprocess. Machining which is essentially parallel with the surface layerand extends to a depth of e.g. 0.1 mm under the surface layer may beadvantageous since the uncovered core surface will then contain a greatamount of melamine. The quality properties of the decorative jointportion may thus be positively affected by a suitable laminating methodbeing used. A larger amount of melamine in the decorative layer, and alonger press cycle and/or machining of the surface of the core so thatit will be more susceptible to melamine, may be used to affect thequality properties of the joint portions. This is also applicable whensurface layers of e.g. high-pressure laminate or wood are glued to acore. Glue penetrates into the upper parts of the core and bonds thefibres. Glue, melamine and other chemicals used in the production offloor elements or floor panels may also be stained, which may be used toobtain decorative effects. The visible joint edges can be machined to anumber of varying shapes, such as rounded, beveled at different anglesand the like. Grooves can be made in the core before or afterlaminating, which are filled with suitable filling materials which havemore suitable properties than does the core as regards, for instance,moisture and decoration. These filling materials can be placed in thecore in the areas which will then constitute visible portions when thesurface layer is removed or when the joint edge is given its finalshape.

The floor surface may be provided with optional decorative grooves. Oneor more parallel grooves may exist at the joint edges and/or between thejoint edges. The grooves may also be rectangular, square, round,elliptic and the like. With a modern production process, advancedpatterns can be made in the floor surface. This technique isparticularly suitable for laminate floors, but may also be used in othertypes of floors.

Additional aspects of the invention comprise floorboards provided withsystems according to the above-described aspects, a floor panel intendedas semi-manufacture for manufacturing such floorboards, and a method formanufacturing such floorboards.

Examples of embodiments of the invention will now be described in moredetail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1a-d illustrate in different steps manufacture of a floorboard.

FIGS. 2a-e illustrate the composition of laminate flooring with asurface of high pressure laminate and direct laminate.

FIGS. 3a-b illustrate examples of different ways of manufacture of adecorative joint portion according to prior art.

FIGS. 4a-b illustrate a decorative joint portion according to theinvention.

FIGS. 5a-c show an alternative embodiment of the decorative jointportion according the invention.

FIGS. 6a-c show different embodiments of the invention.

FIGS. 7a-c show a floorboard according to the invention.

FIG. 8 illustrates a manufacturing method for making decorative grooves.

FIGS. 9a-d illustrate different embodiments of the invention,

FIGS. 10a-e illustrate different embodiments of floorboards manufacturedaccording to the invention,

FIGS. 11a-b illustrate manufacture of decorative joint portions.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIGS. 1a-d show in four steps manufacture of a floorboard. FIG. 1a showsthe three basic components surface layer 31, core 30 and balancing layer32. FIG. 1b shows a floor element 3, where surface layer and balancinglayer have been applied to the core. FIG. 1c shows how floor panels 2are made by dividing the floor element. FIG. 1d shows how the floorpanel 2 after machining of its edges obtains its final shape and becomesa completed floorboard 1 with a joint system 7, 7′, which in this caseis mechanical, on the long sides 4 a, 4 b.

FIG. 2a shows manufacture of high pressure laminate. A wear layer 34 ofa transparent material with great wearing strength is impregnated withmelamine with aluminum oxide added. A decorative layer 35 of paperimpregnated with melamine is placed under this layer 34. One or morereinforcing layers 36 a, 36 b of core paper impregnated with phenol areplaced under the decorative layer 35 and the entire packet is placed ina press where it cures under pressure and heat to an about 0.5-0.8 mmthick surface layer 31 of high pressure laminate. FIG. 2c shows how thissurface layer 31 can then be glued together with a balancing layer 32 toa core 30 to constitute a floor element 3.

When making compact laminate, the entire core consists of reinforcinglayers.

FIGS. 2d and 2e illustrate direct lamination. A wear layer 34 in theform of an overlay and a decorative layer 35 of decoration paper, whichare impregnated with melamine, are placed directly on a core 30, afterwhich all three parts and, as a rule, also a rear balancing layer 32 areplaced in the press where they cure under heat and pressure to a floorelement 3 with a decorative surface layer 31 having a thickness of about0.2 mm. The upper part 25 of the core closest to the decoration paper 35will be impregnated with melamine in lamination. As a rule, 0.2 mm ofthe core closest to the surface layer is impregnated with melamine. Thispart has better properties than other parts of the core and is lesssensitive to moisture, impact and wear. It may thus be an advantage ifthe decorative joint portion is formed in this part of the core. A gluelayer used for joining of surface layer and core may have the samefunction.

FIGS. 3a-c show manufacture of a decorative joint portion 20, 21according to prior art. FIG. 3a shows the floor element 3 before sawing.Owing to uncontrolled swelling of the decoration paper, the embossing ofthe surface has not occurred with sufficient precision. FIG. 3b showsthe edges of the floorboard after sawing and machining. Decoration andembossing deviate significantly from the intended position.

FIGS. 4a-b show manufacture of a decorative joint portion 20, 21according to the invention. FIG. 4a shows a floor panel afterlaminating, but before sawing. The decorative joint portion 20, 21 hasbeen made by machining of the joint portions. The decorative surfacelayer 35 has been removed and the reinforcing layer 36 a is visible andconstitutes a decorative joint portion 20, 21. The edges of thefloorboard are in this embodiment provided with a mechanical lockingsystem consisting of a groove 9 and a tongue 10 which lock verticallyand a locking groove 12 and a locking element 8 which lock horizontally.The joint edges may have optional joint systems. The decorative jointportions 20, 21 have in this embodiment essentially the same width anddepth. The width and depth may also be different between the two jointportions 20, 21.

FIGS. 5a-c show in detail the different steps of manufacture forproviding a decorative joint edge portion which in this embodimentconsists of a wood-fibre-based core 30 which is impregnated and/orstained before lamination. According to FIG. 5a , the stainedimpregnating material 24 is applied, for instance with a nozzle 40, tothe core surface 33 in the portions which in the completed floorboardwill constitute the decorative joint portions 20, 21. A considerablepart of the upper part of the intended joint edge is impregnated, sothat a stained and preferably moisture-proof core portion is formed.Vacuum 46 can be used to facilitate penetration of impregnatingmaterial.

FIG. 5b shows the floor element 3 with a surface layer 31, a balancinglayer and the intended saw cut 45.

FIG. 5c shows the edges of the floor panel 1, 1′ after sawing andmachining.

The surface layer 31 has been partially removed so that the stained anduncovered core is visible and constitutes a decorative joint portion 20,21. As an alternative to impregnation before lamination, the joint edgeportions in FIG. 5c can be impregnated with, for instance, differenthydrophobing substances that are applied after machining. Suchsubstances can be petroleum-based wax, mineral oil and the like,optionally with pigments added. They can, for instance, be applied inseveral steps with supply of energy to facilitate penetration andhardening.

FIGS. 6a-c illustrate embodiments of the invention.

The machining of the decorative joint portion can according to FIG. 6aextend to a depth P2, counting from the horizontal plane HP, which is atleast 0.1 times the thickness of the surface layer 31. The sum of theextent P1 of the machining in the joint portions of the two floorboards1, 1′, counting from the vertical plane VP and inwards to thefloorboards, according to FIGS. 6a and 6b is preferably also about 0.1times the floor thickness T or greater. Such a decorative joint portionis suitable to resemble a joint gap between, for instance, two woodblocks. The uncovered reinforcing layer 36 a according to FIG. 6a or theuncovered core surface in the two joint edges, according to FIG. 6b ,VP, may also have an extent counting from the vertical plane, whichcorresponds to about 0.25 times the thickness T of the floorboard. Sucha decorative joint portion is suitable to resemble the joint between twostone slabs. A plurality of alternatives are feasible.

The joint edges between two adjoining floorboards 1, 1′ may, forinstance, have one or more decorative joint portions which together havea visible width of 0.2 to 10 mm. In FIG. 6a , two adjoining edges formin the joined position a decorative groove with a bottom surface 20, 21and lateral surfaces 22, 23. The lateral surfaces 22, 23 have an angleA1, A1′ to the horizontal plane HP which is greater than the angle A2,A2′, A3, A3′ of the bottom surface 20, 21. The angle of the lateralsurfaces may preferably vary between 20 and 120 degrees and the angle ofthe bottom surface may preferably vary between 0 and 30 degrees. Thelateral surfaces and the bottom surface may have, but need not have, thesame angle. A specific feature of this embodiment is that the lateralsurface 22, 23 has a higher angle than the bottom surface 20, 21. It isadvantageous if the lateral surfaces have an angle of 40-60 degrees.This reduces tool wear. It is also advantageous if the bottom surface20, 21 is essentially parallel to the horizontal plane. By essentiallyparallel is meant an angle of about 0-10 degrees to the horizontalplane. It is also advantageous if the bottom surface 20, 21 is plane orinclined downwards away from the surface at an angle A3, A3′.

FIG. 6c shows how beveled and reinforced joint portions 80, 81 can beformed by grooves being made in the core before or after lamination andwhere these grooves are then filled with a decorative filling material80, 81 which then is formed by machining to decorative and preferablymoisture-proof portions.

By selecting a filling material which in terms of colour corresponds tothe decoration of the surface, it is possible to provide beveled jointedges which as to appearance resemble, for instance, homogeneous woodenflooring with beveled joint edge portions. Similar grooves can also bemade between the joint edge portions. As an alternative to fillingmaterial, wood, wood-based boards, plastic, compact laminate and thelike may be used. These materials can be joined in the grooves.

FIGS. 7a-c show how grooves with bottom surfaces 20 a, 20 b according tothe invention can be manufactured and positioned optionally on thesurface of the floorboard between the decorative joint portions 20.Preferably, such grooves 20 a, 20 b as intend to resemble the decorativejoint portions 20 at the joint edges of the floorboard should have awidth which is 2 times the width of the joint portion 20 so that alldecorative joint portions and grooves will have the same appearance oncethe floorboards are joined.

FIG. 8 shows how the decorative joint portions according to FIG. 7 canbe manufactured. The outer joint edge portions 20 of the floorboard aremanufactured by the floorboard being passed through milling machinesfixed between chains 50, 51 and bands 60, 61, as a rule first through afirst machine that machines the long sides, and then through a secondmachine that machines the short sides. The tools with their respectivemilling motors 70, 72 are according to prior art located outside thechains and machine the joint edges. As a rule, use is made of up to fivetools on each side, which at different angles machine the joint edges.To rationally manufacture a floorboard according to the invention withdecorative grooves between the joint edges, it must be possible toperform machining of the surface of the floorboard also between thechains 50, 51. According to the invention, this is most convenient madeby one or more milling motors being provided with extended tool shaftsso that the milling motors can be positioned outside the chain while atthe same time the tool 71 performs machining between the chains. This isadvantageous in particular when manufacture is to be performed ofdecorative grooves which are close to the joint edges. Separate millingmotors can also be placed between the chains 50, 51. For rationalmanufacture of a floorboard with a mechanical locking system and withdecorative joint portions at the joint edges and/or between the jointedges, it is as a rule necessary for the number of machining motors andtools on each side to be increased to six. Manufacture can be still morerational if the number of tools is increased to between six and eight oneach side. The tool 71 which machines the groove in the surface of thefloorboard between the joint edges should operate vertically, i.e.perpendicular, to the surface of the floorboard. The tools machining thejoint edges can operate vertically, horizontally or at different angles.

Manufacture of floorboards, especially laminate flooring, according tothese preferred methods is not known and does not exist today. It goeswithout saying that the decorative grooves can also be made in aseparate operation, but this causes a higher cost and considerablygreater variation than in the case where all parallel decorative groovesare made in the same machine in one operation. The accuracy of thegrooves in depth and side can with the preferred manufacturing methodaccording to FIG. 8 be made with a tolerance of a few hundredths of amillimeter.

FIGS. 9a-d show how a decorative groove 133 can be formed on merely oneedge of two joined floorboards 1, 1′. This embodiment has severaladvantages. The number of tools can be reduced and the joint gap will beless visible. In FIG. 9a , the lateral surfaces 22 and 23 areperpendicular to the horizontal plane HP and the bottom surface 21 isparallel to the surface. In FIG. 9b , the lateral surfaces 22 and 23 areundercut and angled according to lines 11 a, 11 b. An angled lateralsurface 22 may conceal a possible play between the upper joint edges ofthe floorboards. FIG. 9c shows an example of an angled bottom 21 andlateral surface 23. FIG. 9d shows merely a horizontal joint system. Thedecorative groove 133 has an angled 22 and a rounded 23 lateral surface.All preferred embodiments of the joint edges according to FIGS. 9a-9dcan be combined. It is obvious that other angles, radii, depths andwidths can be used within the scope of the invention.

FIG. 10a shows a floorboard with a decorative groove on one long side133 a and one short side 133 b. FIG. 10b shows a decorative groove onmerely one long side 133 a. FIGS. 10c and 10d show a floor whichconsists of the floorboards according to the Figures above. FIG. 10eshows two parallel grooves 135, 133 a and 134, 133 b on the long sidesand short sides. In this embodiment, the grooves have different widths.The floorboard has in this embodiment also an elliptic groove 136 in thesurface.

It is obvious that all the preferred embodiments can be freely combinedwith each other and that the grooves can be given optional designs interms of number, width, depth, shape in all three dimensions etc. Thefloorboards can be designed so that they can be connected, for instance,long side against long side, short side against short side or long sideagainst short side. The joint systems and/or the decorative grooves canbe mirror-inverted and laying can take place in herringbone pattern withfloorboards that need not necessarily have parallel opposite sides.

FIG. 11a shows how the decorative joint portion can be formed in, forinstance, a laminate floor by means of a diamond tool TP1 which in thisembodiment operates at an angle TA of about 45 degrees to the horizontalplane HP. The aluminum oxide in the wear layer of the laminate causesgreat wear in the point WP. This problem can be reduced if the form ofthe tool is stepped. When part of the diamond is worn out, the tool canbe moved to position TP1′ according to FIG. 11b . The tool can also bemoved vertically in small steps of e.g. some hundredths of a millimeter.The depth of the groove will then vary, but differences of a few tenthsof a millimeter are hardly visible, especially in cases where thedecorative joint portion is formed on only one of the two adjoiningedges. The tool TP1 can operate at other angles. In this embodiment, thethickness of the surface layer is about 0.2 mm, the width P1 of thegroove about 1 mm, the depth P2 of the groove about 0.3 mm and the depthof penetration of the melamine 25 under the surface layer between 0.2and 0.4 mm. Such a decorative joint portion is, inter alia, suitable foruse in floorboards having a format corresponding to parquet blocks andbeing laid in parallel rows, diamond pattern or herringbone pattern. Inthese cases, decorative joint edges may be convenient to arrange on onlyone long side and one short side of each floorboard. As a rule, the coreis impregnated with a colour pigment which is darker than the surface ofthe floorboard.

The invention claimed is:
 1. A floorboard comprising a core, wherein thecore comprises a plastic material, and at least one surface layerarranged on an upper side of the core, an outer part of the surfacelayer constituting a horizontal plane, said surface layer comprises adecorative layer and a reinforcing layer, the reinforcing layer beingarranged under the decorative surface layer, wherein at least at twoopposite parallel joint edge portions of the floorboard have aconnecting device for joining the floorboard with similar floorboards ina vertical and horizontal direction, wherein a joint edge portion of thefloorboard comprises a decorative joint portion, the decorative jointportion comprises a surface of the reinforcing layer, and wherein thesurface of the reinforcing layer is essentially parallel to thehorizontal plane.
 2. The floorboard as claimed in claim 1, wherein thereinforcing layer extends from a vertical joint plane and inwards to thefloorboard a distance at least 0.1 times the thickness of thefloorboard.
 3. The floorboard as claimed in claim 2, wherein thereinforcing layer is positioned at a distance from the horizontal plane,the distance being at least 0.1 times the thickness of the surfacelayer.
 4. The floorboard as claimed in claim 1, wherein the reinforcinglayer is positioned at a distance from the horizontal plane, thedistance being at least 0.1 times the thickness of the surface layer. 5.The floorboard as claimed in claim 1, wherein the connecting device isformed for mechanical joining of neighboring floorboards about avertical plane both perpendicular thereto and perpendicular to the frontside of the floorboard.
 6. The floorboard as claimed in claim 1, whereinthe floorboard is quadrilateral and has a surface layer of a plasticmaterial and a decorative joint edge portion at opposite joint edgeportions.
 7. The floorboard as claimed in claim 1, wherein theconnecting device is configured for joining a floorboard with apreviously installed floorboard by inward angling and/or snapping-in toa locked position.
 8. The floorboard as claimed in claim 1, wherein thedecorative layer comprises a decorative plastic material.
 9. Thefloorboard as claimed in claim 1, wherein the reinforcing layercomprises a plastic material.
 10. The floorboard as claimed in claim 1,wherein the surface of the reinforcing layer at the decorative jointportion has an appearance and structure that deviate from the remainingsurface of the floorboard.
 11. A floorboard, having a core of a plasticmaterial and at least one surface layer arranged on an upper side of thecore, outer parts of the surface layer constituting a horizontal plane,said surface layer comprises a decorative layer, wherein at least at twoopposite parallel joint edge portions of the floorboard have aconnecting device for joining the floorboard with similar floorboards ina vertical and horizontal direction, wherein a joint edge portion of thefloorboard comprises a decorative joint portion, wherein the decorativejoint portion comprises a surface of the core, and wherein the surfaceof the core is parallel to the horizontal plane.
 12. The floorboard asclaimed in claim 11, wherein the surface of the core extends from avertical joint plane and inwards to the floorboard a distance at least0.1 times the thickness of the floorboard.
 13. The floorboard as claimedin claim 12, wherein the connecting device is configured for mechanicaljoining of neighboring floorboards about a vertical plane bothperpendicular thereto and perpendicular to the front side of thefloorboard.
 14. The floorboard as claimed in claim 11, wherein theconnecting device is configured for mechanical joining of neighboringfloorboards about a vertical plane both perpendicular thereto andperpendicular to the front side of the floorboard.
 15. The floorboard asclaimed in claim 11, wherein the floorboard is quadrilateral and has asurface layer of a plastic material.
 16. The floorboard as claimed inclaim 11, wherein the connecting device is configured for joining afloorboard with a previously installed floorboard by inward anglingand/or snapping-in to a locked position.
 17. The floorboard as claimedin claim 11, wherein the surface of the core at the decorative jointportion has an appearance and structure that deviate from the remainingsurface of the floorboard.